Convertible multi-color printing machine for the rectoverso printing of especially bank notes

Abstract

The printing machine is composed of two essentially identically constructed halves which each have an impression cylinder (4, 14), an image transfer cylinder (6, 16) resting against this, a blanket cylinder (7, 17) and a collect-printing plate cylinder (5, 15). In the offset-printing position, the blanket cylinder (7, 17) rests against the impression cylinder (4, 14) and is inked by offset plate cylinders, while the collect-printing plate cylinder (5, 15) is inoperative. In the collect-printing position, the blanket cylinder (7, 17) is moved away from the impression cylinder (4, 14), is inked by color selector cylinders (8, 18) and itself inks the collect-printing plate cylinder (5, 15) which rests against the image transfer cylinder (6, 16). Moreover, in both printing positions, the image transfer cylinder (6, 16) is inked by the plate cylinder (10, 20) of an additional single-color printing unit. The paper first loops partially round the impression cylinder (4) of the first machine half and is thereby printed directly on one side by the image transfer cylinder (6) and, in the offset-printing position, also by the blanket cylinder (7) and then loops partially round the impression cylinder (14) of the second machine half, the other side of the paper being printed in a similar way.

I claim: 
     
       1. A convertible multi-color printing machine for the recto-verso printing on paper, comprising: a first and a second cooperating impression cylinder (4, 14) arranged and constructed to pass said paper (1) therebetween and to apply a multi-colored image on a respective side of said paper;   a plurality of inking units (9), each inking unit having a different color;   a plurality of convertible cylinders (8), each convertible cylinders being inked by a corresponding inking unit (9);   converting means for converting said convertible cylinders (8) to one of color selecting cylinders and offset plate cylinders;   a first and a second blanket cylinder (7, 17) having a periphery, with said convertible cylinders (8) being arranged around and in contact with said periphery;   blanket cylinder mounting means for selectively mounting said first and said second blanket cylinder into one of an offset printing position in which said first and said second blanket cylinders (7, 17) contacts one of said first and second impression cylinders (4), and a collect printing position in which first and second blanket cylinders (7, 17) are spaced away from said first and second impression cylinders (4, 14);   first and second image transfer cylinders (6, 16) in contact with said one of said first and second impression cylinders (4, 14) for applying a multi-colored image thereon;   a first and a second collect plate cylinder (5, 15) carrying a collect printing plate;   collect plate mounting means for selectively mounting said first and said second collect plate cylinders (5, 15) to an operative position and an inoperative position, in said operative position said first and second collect plate cylinders (5, 15), respectively, being in contact with said first and second blanket cylinders (7, 17), respectively so that said first and second collect printing plate cylinders (5, 15) are inked by said first and second blanket cylinders (7, 17), respectively, in said collect printing position, and with said first and second image transfer cylinders (6, 16) for picking up said multi-colored image; and   an additional single-color printing unit having an additional plate cylinder (10) with a single color image and   an additional inking unit (11), said additional single-color printing unit being in contact with one of said first and second image transfer cylinders (6, 16) for transferring said single color image thereto;   means for conveying said paper (1) to be printed first through a nip formed between said first impression cylinder (4) and said first image transfer cylinder (6) and through a nip formed between said first impression cylinder (4) and said first blanket cylinder (7), then through a nip formed between said first and second impression cylinders (4, 14) and then through a nip formed between said second impression cylinder (14) and said second image transfer cylinder (16) and through a nip formed between said second impression cylinder (14) and said second blanket cylinder (17).   
     
     
       2. A convertible multi-color printing machine for the recto-verso printing on paper, comprising: a first and a second cooperating impression cylinder (4, 14) arranged and constructed to pass said paper (1) therebetween and to apply a multi-colored image on a respective side of said paper;   a first and second group of inking units (9, 19) of different colors;   a first and a second group of convertible cylinders (8, 18), each convertible cylinders being inked by a corresponding inking unit (9, 19);   converting means for converting said convertible cylinders (8, 18) to one of color selecting cylinders and offset plate cylinders;   a first and a second blanket cylinder (7, 17) each having a periphery, with said convertible cylinders (8, 18) being arranged around and in contact with the periphery of one of said blanket cylinders (7, 17);   blanket cylinder mounting means for selectively mounting said first and second blanket cylinders (7, 17) into one of an offset printing position in which each of said blanket cylinders (7, 17) contact one of said first and second impression cylinders (4, 14), and a collect printing position in which said first and second blanket cylinders (7, 17) are spaced away from said first and second impression cylinders (4, 14);   a first and a second image transfer cylinders (6, 16), each being in contact with one of said first and second impression cylinders (4, 14), respectively, for applying a multi-colored image thereon;   a first and a second collect plate cylinder (5, 15) each carrying a collect printing plate;   collect plate mounting means for selectively mounting said first and second collect plate cylinders (5, 15) to an operative position and an inoperative position, in said operative position each of said first and second collect plate cylinders being in contact with said first and second blanket cylinders (7, 17), respectively, so that the respective collect printing plate is inked by one of said first and second blanket cylinders (7, 17) in said collect printing position, and with of one said first and second image transfer cylinders (6, 16) for picking up said multi-colored image; and   two additional single-color printing units, each having additional plate cylinders (10, 20) with a single color image and an additional inking unit (11, 21), each said additional single-color printing unit being in contact with one of said first and second image transfer cylinders (6, 16) for transferring said single color image thereto;   means for conveying said paper (1) to be printed first through a nip formed between said first impression cylinder (4) and said first image transfer cylinder (6) and through a nip formed between said first impression cylinder (4) and said first blanket cylinder (7), then through a nip formed between said first and second impression cylinders (4, 14) and then through a nip formed between said second impression cylinder (14) and said second image transfer cylinder (16) and through a nip formed between said second impression cylinder (14) and said second blanket cylinder (17).   
     
     
       3. A printing machine as claimed in claim 2 wherein said first and second impression cylinders (4, 14) include drying means (25). 
     
     
       4. A printing machine as claimed in claim 2 wherein said second impression cylinder (14) includes a metallic surface. 
     
     
       5. A printing machine as claimed in claim 2 wherein said first impression cylinder (4) includes a metallic surface, said second impression cylinder (14) includes an offset rubber blanket, and wherein said first and said second impression cylinders (4, 14) press against each other thereby providing in-register guidance for said paper. 
     
     
       6. A printing machine as claimed in claim 2, where said second impression cylinder (14) has an ink-repellant surface. 
     
     
       7. A printing machine as claimed in claim 6 wherein said ink-repellant surface comprises a metal layer with a dampening means, said ink repellant surface thereby acting as a wet offset printing plate. 
     
     
       8. A printing machine as claimed in claim 2, wherein said second impression cylinder (14) has a surface of chromium with a micro-fine grain. 
     
     
       9. A printing machine as claimed in claim 8 wherein said impression and blanket cylinders (4, 14, 7, 17) have a diameter three times larger than the diameter of said collect plate cylinders (5, 15, 10, 20).